1. Field of the Invention
This invention relates to an ink jet ink, an ink jet recording method, an ink cartridge, a recording unit and an ink jet recording apparatus.
2. Description of the Related Art
When images are formed by using an ink jet recording method, there may come about a state that ink is not ejected for a certain time period from ejection orifices of a recording head in a process of scanning of the recording head. That is, intermittent ejection stability may be not well achievable.
In order to resolve such a problem, inks as shown below are proposed. For example, Japanese Patent Laid-open Application No. H03-255171 discloses a report relating to an ink which contains an alkylene glycol having 7 or more carbon atoms. Japanese Patent Laid-open Application No. 2000-297237 also discloses a report relating to an ink which contains an ethylene glycol type organic solvent. Japanese Patent Laid-open Application No. H05-70726 further discloses a report relating to an ink which contains a dicarboxylic acid monoester.
Japanese Patent Laid-open Application No. 2005-298813 discloses, as an ink which can keep recorded materials from curling and also can achieve ejection stability, a report relating to an ink which contains water-soluble compounds different in water-retentive force under environments of stated temperature and humidity. Japanese Patent Laid-open Application No. 2007-39680 discloses, as an ink which can achieve ejection stability, a report relating to an ink which contains water, a coloring material, 1,5-pentanediol and a humectant or an ink having a property that it changes into a liquid from a gel or solid depending on conditions such as temperature and humidity.
About the conventional inks as above, the present inventors have ascertained how far they have the intermittent ejection stability. As the result, they have found the following. That is, these inks all intend to improve intermittent ejection stability in an environment of low temperature and low humidity as having conventionally been so aimed. Hence, these have been found to have no problem even where they are used in an ink jet recording apparatus of about 10 pL (picoliters) in ejection volume in an environment of, e.g., low temperature and low humidity, normal temperature and normal humidity, or normal temperature and low humidity. Stated specifically, these inks have been found to have no problem on the intermittent ejection stability in an environment of normal temperature and normal humidity, such as temperature 25° C. and relative humidity 60%, in an environment of normal temperature and low humidity, such as temperature 25° C. and relative humidity 20%, or in an environment of low temperature and low humidity, such as temperature 15° C. and relative humidity 10%. It should be noted that, the problem of the intermittent ejection stability resulting from the evaporation of water or the like hardly arises under a high-humidity (for example, relative humidity of 80 to 90%) irrespective to the temperature.